Electric field modulation of visible and ultraviolet nanoscale lasers consisting of single CdS or GaNnanowires has been achieved using integrated, microfabricated electrodes. Modulation of laser emission intensity is achieved with no detectable change in the laser wavelength. The devices can also be operated below the lasing threshold to modulate the intensity of light propagating within the nanowirewaveguide. Studies of the electric field dependence in devices of varied geometry indicate that modulation is due to an electroabsorption mechanism. These findings expand opportunities for multicolor, nanowire-based photonic devices and circuits.

Strong polarization-conserving holographicscattering was observed in a photopolymer-dispersed liquid crystal film fabricated from the UV curable mixture of commercially available constituents. During the photopolymerization process a bright corona of diffracted light evolves around the pump beam. The intensity of the rotationally symmetric light distribution increases upon exposure. By rotating the sample, two characteristic diffraction rings appear which can be explained by the Ewald sphere construction. Our results demonstrate that the associated parasitic holograms are very pronounced. Hence, their presence must be accounted for whenever preparing and utilizing holographicpolymer-dispersed liquid crystals in any application.

Stable single-longitudinal-mode laser pulses and instability of two-longitudinal-mode oscillation due to the spatial hole-burning effect were observed experimentally in a laser-diode pumped microchip self--switched laser. We modified the multimode rate equations by including the spatial hole-burning effect in the active medium and the nonlinear absorption of the saturable absorber. The numerical simulations of the mode-competition dynamics of two-mode laser are in good agreement with the experimental data. Instability induced by the mode-competition dynamics was investigated by the evolution of the inversion population and the bleaching and recovery of the inversion population of the saturable absorber.

Electric field modulation of visible and ultraviolet nanoscale lasers consisting of single CdS or GaNnanowires has been achieved using integrated, microfabricated electrodes. Modulation of laser emission intensity is achieved with no detectable change in the laser wavelength. The devices can also be operated below the lasing threshold to modulate the intensity of light propagating within the nanowirewaveguide. Studies of the electric field dependence in devices of varied geometry indicate that modulation is due to an electroabsorption mechanism. These findings expand opportunities for multicolor, nanowire-based photonic devices and circuits.

Using the plasma model recent developed by the authors, this study predicts the existence of a constant ablation-depth zone with respect to fluence in femtosecond laserablation of dielectrics, which has also been observed experimentally. It is found that the value of the constant ablation depth is significantly decreased by the pulse train technology. Repeatable nanostructures can be achieved with the parameters in the constant ablation-depth zone of a femtosecond pulse train, even when the laser system is subject to fluctuations in fluences.

A near-field planar solid immersion mirror (PSIM) has been developed and applied to the writing and reading of marks in a phase-change material. Light focusing of a PSIM is realized by a two-dimensional parabolic reflective surface integrated in a planar waveguide. Using a PSIM fabricated out of a waveguide consisting of a core layer and a cladding layer on an substrate, we have recorded marks with dimensions of .

This letter describes the design, fabrication, and experimental results of a micro solid polymerdye laser designed on the basis of a guided mode resonant grating (GMRG). The resonant condition of GMRG includes the second-order resonance of the distributed feedback cavity. A surface laser emission was obtained in a patterned region by the pulsed-laser pumping. The grating was fabricated by the electron beam lithography and the fast atom beam etching. Dye (rhodamine 6G)-doped poly(methylmethacrylate) was spin-coated on the grating. The laser oscillation occurred in the direction vertical to the grating plane with a sharp peak (-value ) in a single mode designed by the GMRG analysis.

A method to fine-tune photonic crystaldefect cavities is developed based on successive oxidation and wet etching cycles. Photonic crystal microcavities based on InP membranes are oxidized using an ultraviolet (UV)/ozone treatment, and the oxide is subsequently removed using a hydrofluoric acid solution. Each oxidation/etch cycle consumes a thin layer of InP directly exposed to the UV/ozone, enlarging the radius of holes in the photonic crystal and decreasing the membrane thickness. The method is applied to single missing air-hole defect cavities with embedded InAsquantum dots, permitting measurement of the resonant frequency tuning in emission. Defect mode energies were found to blueshift, consistent with finite-difference time-domain simulations. A tuning range of was obtained after .

We demonstrate a subwavelength spherical resonator at microwave frequencies designed to mimic the electromagnetic behavior of a negative permittivity sphere. The structure, which has a radius of (where is the resonant wavelength), consists of an axially symmetric array of noninterconnected conducting elements forming a resonant spherical object. The structure exhibits many of the properties inherent to negative permittivity spherical resonators, the most notable being a very strong coupling to radiation modes despite being much smaller than the wavelength. This characteristic is quantified by the radiation-factor, which was observed to be near 1.5 times the theoretical limit in some of the measured samples, matching the performance achievable in a negative permittivity sphere of comparable electrical size. These resonators may find application in the design of electrically small antennas, as well as in the experimental “simulation,” at microwave frequencies, of nanophotonic device concepts based upon localized plasmon resonances in metal nanoparticles.

A broad-area midinfrared interband cascade (IC) laser has been demonstrated with a threshold current as low as at . Despite exhibiting a large specific thermal resistance ( at ), the device delivered cw power near /facet at and at and lased in cw mode up to . A -long laser delivered cw power of /facet at and at , and had power efficiency as high as 26% at . Narrow mesa stripe IC lasers had relatively higher threshold current density, yet lased at temperatures up to 237 and in cw and pulsed modes, respectively. The feasibility of cw operation at higher temperatures and directions for improving IC laser performance are discussed based on the experimental data.

A high-efficiency and high-power oscillator was developed based on the microthickness slab structure with high aspect ratio to obtain one-dimensional temperature gradient and to reduce the temperature increase in the crystal. Laser output power of was obtained in cw oscillation with 42% optical conversion efficiency at a pump power of .

Nonlinear diffraction in three-dimensional silicon-filled photonic crystals of opals is studied. Efficient backward second-harmonic generation (SHG) is observed in the specular direction upon the fundamental radiation reflection from the (111) face of the face-centered-cubic opal lattice. Tuning the fundamental wavelength across the photonic band gap(PBG) results in the 20-times increase of the second-harmonic intensity. The SHG peak has the width of approximately and is located at the long-wavelength edge of the PBG.

We demonstrate all-optical switching in the telecommunication band, in siliconphotonic crystals at high speed , with extremely low switching energy (a few ), and high switching contrast . The devices consist of ultrasmall high-quality factor nanocavities connected to input and output waveguides. Switching is induced by a nonlinear refractive-index change caused by the plasma effect of carriers generated by two-photon absorption in silicon. The high-quality factor and small mode volume led to an extraordinarily large reduction in switching energy. The estimated internal switching energy in the nanocavity is as small as a few tens of fJ, indicating that further reduction on the operating energy is possible.

We demonstrate very-long-wavelength infrared type II superlatticephotodiodes with a cutoff wavelength of . We observed a zero-bias, peak Johnson noise-limited detectivity of at 77 K with a 90%–10% cutoff width of 17 meV, and quantum efficiency of 30%. Variable area diode zero-bias resistance-area product measurements indicated that silicon dioxide passivation increased surfaceresistivity by nearly a factor of 5, over unpassivated photodiodes, and increased overall uniformity. The bulk at 77 K was found to be , with increasing more than twofold at 25 mV reverse bias.

An integrated optics called terahertz (THz) pigtail, which is comprised of an emitter, an optically transparent launching media, and a waveguide, is devised and fabricated. The InAs emitter under a magnetic field is coupled to the launching media using silicone grease, an index matching liquid. The launching media, a lens duct made from a polymer based on poly 4-methyl pentene-1 (commonly known as TPX), is designed based on the concept of guiding THz radiation into Teflon photonic crystal fiber(PCF)waveguide by means of total internal reflection. It is found that the constructed THz lens duct is able to channel and couple the THz radiation into the PCFwaveguide with a loss of . The results here show that the idea of using the THz pigtail can be a potential means of effectively directing THz radiation.

With a rate of , thin-film has been deposited on with nanosecond laser pulses at . The samples revealed rectification with an uncommon power dependence on the forward bias. Furthermore, we noticed that the intrinsic photocurrent spectra sensitively depend on the deposition time. Increasing this duration from one to three hours shifts the maximum of the spectral device response from GaAs to Si. The result stresses the flexibility of pulsed-laser deposition to alter device properties in extremely simple ways.

A metallic tip probe that gives high optical intensity and small spot size with a small background light is proposed and simulated. The proposed tip probe provides advantages of both the aperture probe and the apertureless probe currently used in the scanning near-field optical microscope. The tip probe is illuminated by surface plasmonpolaritons transmitted through the I-shaped aperture in a pyramidal structure on a thick metallic screen. Scattering of optical waves by this structure is solved numerically using a volume integral equation by generalized conjugate residual iteration and fast Fourier transformation. The proposed tip probe is shown to simultaneously provide both high near-field intensity and small spot size with a small background light.

The effect on solar cell performance of planar converters containing quantum dots(QDs) as wavelength-shifting entities on top of multicrystalline silicon cells was investigated by means of model studies with varying incident spectra. These included global, direct, and diffuse spectra with Air Mass (AM) values ranging from 1 to 10. In case of AM1.5, a planar converter with QDs emitting at yields a short-circuit current increase of 6.3%, 9.6%, and 28.6% for direct, global, and diffuse irradiation, respectively, as a result of the larger blue/green content of diffuse spectra with respect to direct and global ones. For other AM values, similar results are calculated, with a lower increase toward high AM values.

Optical microcavities provide a possible method for boosting the detection sensitivity of biomolecules. Silica-based microcavities are important because they are readily functionalized, which enables unlabeled detection. While silicaresonators have been characterized in air, nearly all molecular detections are performed in solution. Therefore, it is important to determine their performance limits in an aqueous environment. In this letter, planar microtoroid resonators are used to measure the relationship between quality factor and toroid diameter at wavelengths ranging from visible to near-IR in both and , and results are then compared to predictions of a numerical model. Quality factors in excess of , a factor of 100 higher than previous measurements in an aqueous environment, are observed in both and .

An organic photonic crystal(PC) with a nanocavity has been fabricated on a membrane with air holes. The emission peak caused by the resonant mode of the nanocavity was clearly observed from the nanocavity area of the PC. The emission peak corresponded to degenerated dipole modes from comparison between measured and calculated results. Modification of a nanocavity caused the peak splitting of dipole modes and the appearance of a peak corresponding to a hexapole mode. The emission peak with a quality factor of about 1000 was obtained from a PC with a modified nanocavity.

We have studied the exciton localization dynamics in epitaxial films with different In compositions (, 0.05, and 0.09) by means of optical Kerr-gate time-resolvedphotoluminescence(PL) spectral measurements. By changing excitation wavelength of laser pulses, films are resonantly excited around their excitonenergies at . Under the resonant excitation, the PL dynamics is sensitive to the In composition of the sample and the excitation laser intensity. In the low In composition samples, the formation time of radiative excitons at localized states is . In the high In composition samples, the gradual redshift of the PL peak energy is observed within several tens of picoseconds. The radiative recombination processes of excitons are discussed.